Footwear having improved block copolymer foxing adhesion



3,473,240 FOGTWEAR HAVING IMPROVED BLOCK COPQLYMER FOXIYG ADHESION .lonW. Martin, Les Aiarnitos, .lohn L. Snyder, Long Beach, and Gienn R.Himes, Torrance, Calif., assignors to Shell Oil Company, New York, N.Y.,a corporation of Delaware No Drawing. Filed Apr. 8, 1968, Ser. No.719,721 Int. Cl. A43h 1/02, 9/00 US. Cl. 36-4 Claims ABSTRACT OF THEDISCLGSURE Footwear assemblies are provided comprising a textile upper,a polymer soling and a block copolymer foxing wherein the foxingadhesion to the upper in wear and under wet conditions is substantiallyimproved by pretreatment of the upper fabric with certain polymericmaterials having a dielectric constant at least as great as that of theblock copolymers, the assemblies having wet peel strength which is atleast 70% of the dry peel strength.

This invention relates to improvements in the bond of foxing to footwearhaving textile uppers. More particularly, it relates to footwear uppersbearing a coating which promotes adhesion of foxing comprising blockcopolymers.

Numerous types of footwear are designed to perform their function undera variety of physical conditions. The sole of some fabric upper shoes isattached to the upper by a foxing strip. While it is reasonably an easytask to design a shoe assembly which has a high bond strength ofpolymeric foxing to fabric under conditions of dry peel measurement, thebond of foxing to fabric often leaves much to be desired in use,especially when exposed to moisture as it is on the foot. This isprobably due in substantial part to the lack of true adhesion of thefoxing material, which is usually nonpolar or substantially so, to thetextile, which is often polar in character, as in the case of cellulosicfibers and the like. Textile top shoes, in particular, are subjected toa number of situations which unless adequately met, result indisintegration of the assembly. Thus, under the influence ofperspiration or rain, the foxing strip around the base of the upper maytend to separate especially at the area of flexing. Also, when washed inthe presence of hot water and detergents, foxing separation may be asevere problem. More specifically, the problem of wet bond strength isespecially apparent in such footwear as canvas topped shoes. In sucharticles it is not only important to maintain a high degree offlexibility, improve abrasion resistance and dry peel strength but alsoand perhaps more importantly to maintain a high foxing to fabric bondwhen the shoes are subjected to fiexure especially in moist conditions.

It is the usual practice in the trade to laminate two layers of canvastogether with a polymeric combining paste and then to bond the canvaslaminate to a thermoplastic or elastomeric sole portion of the shoe witha strip applied either simultaneously or subsequently which is known asa foxing strip. This foxing is the strip of material which covers theupper part of the sole edge and the lower part of the canvas upper edgeWhere the upper and sole meet. In many instances in the past, thecombining paste has been made out of thermoplastics such as PVC orvulcanized material such as vulcanized SBR, polychloroprene and thelike. The vulcanized polymers are highly intractable materials once theyhave been 1 nited States Patent 0 3,4732% Patented Oct. 21, 1969thermoformed. Moreover, it has been found by experience that thesecombining paste compositions lack the ability of physically promotingadherence of block polymer foxing especially under wet conditions.

Canvas top shoes and the like must be marketed under highly competitiveconditions. Consequently any ecomomies which may be effected in themanufacture of the articles improve the competitive position thereof.The necessity for vulcanizing prior art compositions used as foxing orother footwear components reduces this competitive position andconsequently it would be highly desirable to avoid vulcanizing and atthe same time to provide improved bond and especially wet peel strengthfor foxing compounds.

It is an object of the present invention to improve the physicalproperties of footwear assemblies. It is a particular object of theinvention to provide improved footwear as materials to result insuperior wet peel strength.

Now, in accordance with the present invention, an improved shoeconstruction is provided possessing substantially increased foxingadhesion even under wet conditions which comprises, a textile upper, atie coat thereon at least in the area to be contacted by the foxing, afoxing strip and a sole, both the foxing and sole comprising anunvulcanized block copolymer as defined hereinafter. The textiletie-coat foxing assembly must have a Wet peel strength at least as highas the dry peel strength thereof due to the high degree of affinity ofthe tie coat to both the textile and the block copolymer foxingcompound. The tie coat for this purpose must be a polymeric substancehaving the following properties:

(1) A dielectric constant at least equal to that of the block copolymer,i.e., at least about 3.0 at 60 cycles, at 23 C.;

(2) Tensile strength of at least pounds per square inch at 23 C.

The difference between wet and dry peel strength appears to be one ofthe most important defining qualifications. In effect, it describes theadherence of the tie-coat polymer both to the textile upper material andto the block polymer foxing compound under both wet and dry conditionswhich any textile-top footwear will encounter in normal use.

The next most important criterion of the tie coat polymer is withrespect to tensile strength, which should be at least 150 pounds persquare inch (p.s.i.), and preferably at least 350 psi. at 23 C. Thislimitation is based on tensile values obtained on compression moldedtensile specimens at 23 C. using a crosshead speed of 20 inches perminute (ASTM test number D4l2-62T, Die D). The tensile strength valuesgiven and the limitations placed thereon will either be on unvulcanizedor on vulcanided polymers, depending on their common usage in thisrespect.

The chemical classes of polymers especially useful in tie-coat compoundsinclude, among others, polymers of vinyl halides, amine-aldehydecopolymers, phenolics, phenol-aldehyde copolymers, halohydrocarbonpolymers, epoxy resins, cellulose ethers and esters, ABS polymers,polyurethanes, acrylate polymers, methacrylate polymers and the like, aslong as they meet the physical criteria set out hereinbefore. Thefollowing table gives tensile strength, dielectric constant andsolubility parameter data of polymers especially suitable for use intie-coat compounds. A further preferred qualifying description of thetie coat is one which reduces the area of foxing separation by a factorof at least 2, during actual wear tests compared with shoes not havingthe foxing tie coat.

TABLE A.

Tensile Dielectric strength, p.s.i. constant (ASTM D638 (ASTM D150) orASTM D651) 60 cycles Styrene-butadiene 3 AB S 4, 000 2. 4-5. Methylmethaerylates 7, 000 3. -4. 5 Methyl methacrylate-alph rene copolymers.9, 000 3 Ethyl cellulose 2, 000 3-4. 2 Cellulose acetate- 1, 900 3. 5-7.5 Cellulose acetate butyrate. 2, 600 4-5 Epoxy resins 4, 000 3-5. 5Polyvinylidene fluoride 7, 000 8. 4 Melamine-formaldehyde resins. 5, 0007 Nylon 7, 000 4-4. 0 Alkyd reslns 5. 1-7. 5 Silicones 8, 000 3. 3-5. 2Urea-formaldehy 5, 500 7-9. 5 Polyurethanes" 4, 500 7. 6 Polyvinylbuty'ral 500 5. 6 Polyvinyl chloride. 1, 500 3-9 Phenol-formaldehyde.10, 000 5-6. 5 Polychloroprene 3, 000 1 6. 5-8. 1 Polyvinylidenechloride 3T 1 IKC.

The art of processing each of these classes of polymers is well knowninsofar as the necessity of vulcanizing or curing is concerned. Expertsin the art of polymer formulation will be able to determine what, ifany, such treatment is required in each individual case.

It is important to emphasize that, while the tie-coat polymer may bevulcanized, if necessary, it is only contemplated to use unvulcanizedblock copolymers in the foxing and sole compounds. Thus, only a physicalbond (as contrasted to a chemical linkage) unites the foxing with thetextile upper.

While the assembly in its broadest aspects thus contemplates theformation of a high bond strength single textile upper bearing a foxingstrip comprising a block copolymer, a more particular aspect of theinvention contemplates the situation in which two textile sheets arecombined by means of an intervening combining composition. The termcombining compounds is used in the shoe trade for the composition whichis utilized for laminating one layer of textile to at least a secondlayer, resulting in a composite textile especially designed for thepreparation of textile shoe uppers. More particularly, the compositionsperforming the function of combining compounds comprise not only theblock copolymer but compositions in which the block copolymer ismodified with one or more ingredients including especially polystyrene,tackifying resins, hydrocarbon extending oils and/or mineral particulatefillers, as is more particularly described hereinafter in greaterdetail. Other combining compounds may comprise vulcanized SBR,polychloroprene and polyvinyl chloride.

The most important application of the present invention at this time isin the manufacture of sport shoes generally referred to as tennis shoesor the like. The problem of foxing separation referred to hereinafter issubstantially eliminated or largely minimized by the use of the presentinvention. As the data given hereinafter will show, the application of apolymeric tie coat to at least the area of the textile upper contactedby the foxing and thereafter manufacturing shoes such as by injectionmolding of a block copolymer foxing and a soling onto this upper resultsin a surprisingly improved bond of foxing to upper during use.

The textile involved in the articles of the present invention may beeither woven or nonwoven as the case may be and if two or more layers oftextile are present they may be either similar or dissimilar. Thetextile uppers may be impregnated with a superficial amount of blockpolymer, if so desired, for the purpose of improving abrasion resistanceand reducing water permeability.

While uppers often are cotton canvases exclusively, they may becombinations of cotton with synthetic materials or regenerated cellulosesuch as rayon or may comprise at least in part textiles such polyester,nylon and ithe like. The present invention moreover contemplates theformation not only of sport shoe uppers but the preparation ofinnersoles, toe stiffeners, heel stiffeners and clothing interlays.

The block copolymers to be used in foxing and optionally in soling andcombining compounds are either linear or branched, i.e., star-shaped,and have the general configuration Disregarding any residue of acoupling agent, suitable star-shaped molecules could be betterrepresented as AB(BA) If the copolymer is not hydrogenated, the blocks Acomprise poly(vinyl arene) blocks, n is an integer from 1 to 5, whilethe block B is a poly(conjugated diene) block. The blocks A normallyhave number average molecular weights, as determined by intrinsicviscosity measurements which have been correlated with primary molecularweight measurements including osmometry and radio tracer measurements oftritium terminated polymer, of between about 8,000 and 45,000, while theconjugated diene polymer block has a number average molecular weightbetween about 25,000 and 150,000. If the copolymers are hydrogenated,the molecular weight ranges remain in about the same ranges. Twopreferred species of such block copolymers include those having theblock configuration polystyrene-polybutadiene-polystyrene andpolystyrene-polyisoprene-polystyrene as well as their hydrogenatedcounterparts. The hydrogenated counterpart of the second of the abovedefined block copolymers is of special interest, not only because of itshigh stability but because of the elastomeric nature of the hydrogenatedmidsection which resembles that of an ethylene-propylene rubber whilethe end blocks either remain as polyvinyl arene blocks or, ifhydrogenated, become saturated blocks made up of polyvinylcyclohexaneunits. Thus, the fully hydrogenated preferred species has a blockconfiguration which corresponds closely top0lyvinylcyclohexane-ethylone-propylene copolymer-polyvinylcyclohexane.

These particular block copolymers have the unique feature of attainingthe stress-strain properties of an elastomer without the requirementthat it be subjected to curing or vulcanization. Thus, they are sharplydifferentiated from other rubbers such as natural rubber, polybutadiene,SBR and the like which require vulcanization in order to attainsatisfactory stress-strain properties.

The block copolymers of this invention may be the major polymericmaterial utilized in the foxing but they may, if preferred, be modifiedby the presence of other components such as plasticizers or otherpolymeric coating materials. Plasticizers such as rubber extendingmineral oils or esters may be employed and polymers such as polystyrene,polyethylene, polypropylene and the like may be incorporated with theblock copolymers.

The compositions which are contemplated for the present purposeespecially where canvas top sport shoes are concerned includeparticularly at least foxing compounds which are combinations of partsby weight of the subject block copolymers with 5-130 parts by weighteach of polystyrene and extending oil. Normally, still furthermodifications of such compositions are possible and are utilized forimproving the flexibility and reducing the modulus of the compositionsif desired as well as for reducing the overall cost. Thus, the presenceof 5-130 parts by weight of a hydrocarbon extending oil is alsocontemplated as is the presence of a substantial amount of an inorganicfinely divided particulate solid especially in the order of 5-200 partsby weight per 100 parts of the block copolymer.

Polymer extending oils are useful both for the purpose of reducing thecost of the compositions and more particularly for imparting betterprocessing and physical properties thereto. This is especially importantas the average molecular weight of the block copolymer increases. Insome instances in the higher molecular weight ranges processing becomesextremely difiicult at ordinary processing temperature short ofdecomposition temperatures in the absence of extender oils. It ispreferred that the extender oils be those utilized for extending otherpolymers and particularly rubbers and that these have no more than about50% aromatics and greater than about 45% of saturates, usuallynaphthenic types of hydrocarbons.

The extender oils should be utilized in amounts between about 2 and 300parts (preferably 5-130 parts) by weight per 100 parts by weight of theblock copolymer.

Pigments are normally utilized in as large amounts as possible whilestill maintaining desired physical properties; usually this will be anamount between about 25 and 400 parts by weight per 100 parts by weightof the block copolymer.

The incorporation of these materials together may take place on theusual polymer processing mills and internal mixers or in an extrusiontype of apparatus or may be composited by means of other masterbatchingprocesses, particularly a solution masterbatch. In this process asolution of the block copolymer is formed in a solvent which is either anon-solvent or only a partial solvent for polystyrene. Specifically,such a solvent will comprise 21-85% by volume of an open-chainhydrocarbon having from 4-8 carbon atoms per molecule and 79-15% byvolume of a cyclic hydrocarbon having from 5-8 carbon atoms permolecule. The polymer solution (cement) so formed is then combined with5-200 parts by weight of polystyrene and 25-400 parts by weight of thefinely divided particulate solids per 100 parts by weight of the blockcopoly- I mer. The mixture is then subjected to coagulating procedure soas to isolate the solid materials from the solvents. This is besteffected by forcing the mixture into a vessel containing steam and hotwater under such conditions that the solvent is flashed off and thecomposition becomes suspended in a bath of water in the form of crumbs.These are then separated from the water by screening or decantation andsubjected to grinding if necessary to effect relatively uniform particlesize after which the particles are subjected to drying procedures as inmoving belt drier, expander drier or the like. The use of thisparticular type of solvent accentuates the effective ness of thepolystyrene in retaining the finely divided particulate solids.Apparently, the polystyrene exists under these conditions as a gummyhighly swollen material which aids in the incorporation of theparticulate solids.

In accordance with the present invention, the bond of block polymerfoxing to textile uppers is unexpectedly retained even under wetconditions such as encountered in normal wear, wet weather, washing orperspiration by the application of at least a superficial coating orimpregnation on at least on that part of the upper which is later to becontacted with the foxing compound. The materials employed for thispurpose are listed and described hereinbefore. Polyvinyl chlorides areespecially effective. The polyvinyl chlorides, a preferred class oftie-coat polymers in the present assemblies, include thermoplasticpolymers produced by the polymerization of a monomer mixture containingnot less than 70% by weight of vinyl chloride and preferably more than90% by weight thereof. The monomers may comprise entirely vinyl chlorideas the sole monomer. In addition thereto, copolymers and interpolymersof vinyl chloride with minor amounts of one monoolefinic or vinyl typeof comonomers may be utilized. Illustrative comonomers are vinylidenechloride, vinyl acetate, methyl acrylate, styrene, acrylonitrile, methylmethacrylate, ethylene, propylene and others.

While relatively low molecular weight polyvinyl chlorides are preferred,to minimize the necessity of plasticizer, the present invention is notto be restricted to any relatively critical or narrow molecular weightrange. The polymers may be characterized in terms of specific viscosity,intrinsic viscosity or by molecular weights, since all of these arerelated. The molecular weights normally will vary from about 5,000 toabout 50,000 and it is preferred that the approximate average molecularweight be between about 10,000 and 25,000. Intrinsic viscosities willusually vary from about 0.12 to about 0.90. As used herein, the termsspecific viscosity and intrinsic viscosity are calculated values derivedfrom viscosity measurements. Solutions for viscometric study areprepared by dissolving 0.125 gram of the polyvinyl chloride in cc. ofcyclohexanone while mildly heating and agitating on a solution roller.The solutions are then filtered into an appropriate Ubbelohde viscometerpreviously calibrated for the pure solvent. The flow time in seconds forthe solution is determined at three dilutions to obtain flow data at anumber of concentrations. The ratio of the flow time to the flow time ofthe pure solvent is a value known as the reduced viscosity. When theinteger 1 is subtracted from reduced viscosity, one obtains the valueknown as the specific viscosity. When the specific viscosity is dividedby the concentration and the values obtained plotted againstconcentration, the extrapolation of the resulting straight line to zeroconcentration gives the value known as intrinsic viscosity. Since therelation between the logarithm of the intrinsic viscosity values and thelogarithm of the molecular weights is a straight line function, theapproximate molecular weight of any polyvinyl chloride may be readilycalculated from its intrinsic viscosity value. Thus, an intrinsicviscosity value of 0.2 corresponds to a molecular weight ofapproximately 8800 and a value of 1.0 corresponds to a molecular weightof about 58,000. Best foxing adhesion is obtained when the PVC isapplied in amounts between about 0.005 and 0.15 gram per square inch oftextile so treated.

The polyvinyl chloride may be applied to the fabric, and particularly tothe area of the textile upper later to be contacted with the foxingcompound by any desired means such as by dipping or spraying in solventsolution, by a cement or as a latex.

One preferred class of resins utilized as tie-coat polymers in thestructures of the persent invention may be referred to as acid-curedthermosetting aminotriazinealdehyde resins. These include resins formedbetween an amino triazine and an aldehyde and treated under acidicconditions and at a time and temperature sufficient to form awater-insoluble cured resin coating. While the triazine may be mixedwith a variety of proportions of aldehyde to form prepolymers suitablefor acidand heatcuring, it is preferred that l-6 mols of aldehyde beused per mol of aminotriazine.

Suitable triazines include diaminotriazines, triaminotriazines,alkyloldiaminotriazines and alkyldiaminotriazines. Aldehydes such asformaldehyde, propionaldehyde, acetaldehyde, fural and benzaldehyde maybe used. Specifically, the preferred resins are formed between melamine(2,4,6-triamino-l,3,S-triazine) and formaldehyde in mol ratios betweenabout 1:1 and 1:3. Any alkyl substituents on the triazine moleculepreferably have l-8 carbon atoms.

The resins and their curing systems are known. Curing agents arenormally applied to the textile with prepolymers, usually but notnecessarily in an aqueous solution. Water or other sovent is evaporatedand the resin cured to a water-insoluble state by heating at 300-400" F.for 1-30 minutes. Suitable acid-acting catalysts include, for example,mineral acid, ammonium salts such as ammonium chloride and mineral acidsalts of alkaline earth metals such as magnesium chloride. These arepresent in amounts varying between about 1 and about 50 parts by weightper 100 parts of prepolymer.

The resin may be modified by the presence of pigments, plasticizers andtackifying resins such as the phenol formaldehyde or coumarone-indeneresins. The resin on the area to be later contacted with the foxingstrip should preferably be present in an amount based on the area beingso treated of between about 0.002 and 0.04 gram per square centimeter.The resin may be applied to the textile as a solution, as an aerosol oras an emulsion.

The polychloroprenes utilized as another preferred class of tie-coatpolymers, have molecular weights in the order of between about 20,000and 1,000,000 and to predominate in species having molecular weightsbetween about 50,000 and 250,000. They may be utilized either in anunvulcanized condition or they may be compounded with vulcanizers andaccelerators resulting in a vulcanized polychloroprene area. In thelatter case heat for vulcanization is supplied by the injection moldingprocess itself; that is, the polychloroprene coating vulcanizes when itis contacted by the hot block polymer foxing compound. Furthermore, ithas been found advantageous if the polychloroprene is to be vulcanizedto include at least a portion of the vulcanizing agent in the blockcopolymer foxing compound, thus causing a certain amount of chemicalinterlinking between the foxing strip and the area of textile treatedwith polychloroprene. The particularly unexpected feature of the presentinvention 15 to find that the treatment of the textile withpolychloroprene increases the adhesion of the block copolymer foxingstrip even under wet conditions and in spite of the fact that these twopolymers are so dissimilar chemically.

The vulcanizing agents utilized for the vulcanization of polychloropreneare well known in the art and include especially zinc oxide andpreferaby mixtures of 21110 oxide with magnesium oxide, althoughlitharge or red lead may be utilized in place or in addition to thesematerials. Accelerators may be utilized to promote vulcanization ifdesired. Advantages of zinc oxide and other nonsulfur-donatingvulcanizing agents in this system are that they do not vulcanize theblock copolymers herem described. Vulcanization of the block copolymersis not only unnecessary but may be deleterious to physical properties.

EXAMPLE I A cotton canvas laminate was prepared using as the combiningcomposition a vulcanized SBR. The laminate was cut to the shape oftemris shoe uppers and the area of the canvas to be contacted with thefoxing was sprayed with an aersol of polyvinyl chloride (dissolved inketones) having an average molecular weight in the order of about15,000, the aersol medium being Freon. An amount of about 0.04 gram persquare inch of polyvinyl chloride was thus deposited in the foxing areaof the textile upper. The treated uppers were then fitted into aninjection molding shoe manufacturing machine and a block copolymercomposition injected into the mold to simultaneously form the soling andthe foxing. The composition employed for this purpose was as follows:

Parts by wt.

Polystyrene-polybutadiene-polystyrene block polymer(22,000-45,000-22,000 mol. wt.) 100 Mineral oil 108 Polystyrene 60 TiO15 Clay 75 The shoes so prepared were subjected to three washing anddrying cycles. In the washing operation the shoes were washed with acommercial domestic detergent in a domestic washing machine. In thedrying operation the domestic dryer was set at the warm temperaturedrying level. Essentially no change in the foxing adhesion was notedafter this Washing test. Comparable shoes were prepared in which thepolyvinyl chloride treatment was omitted, all other conditions of thepreparation and assembly being identical. After the same washing anddrying cycle, however, it was found that a substantial parting of thefoxing from the canvas upper occurred.

One quarter inch Wide samples of the shoe uppers bearing a foxing strip,prepared as described above, were subjected to a soaking test comprisingimmersion in a 1-2% aqueous laundry detergent solution for 30 minutes atroom temperature. Control specimens bearing no tiecoat were comparedwith specimens bearing 0.01 g. PVC

Peel strength, p.l.i.

Before soak After soak Control, no PVC PVC coated EXAMPLE II Comparativetests were performed on shoe assemblies with and without apolychloroprene treatment. Canvas sheeting was laminated with a curedSBR combining paste to form a canvas laminate which was cut into theform of tennis shoe uppers. The area which was to be contacted with thefoxing strip was treated with a solution comprising 60/40 methyl ethylketone/normal hexane containing 8% by weight of a polychloroprene havinga relatively high viscosity, a fast crystallization rate and lightcolor. The polychloroprene used was of the type which does not containsulfur linkages or a thiuram disulfide, as do some commercial grades.Impregnation was 0.03 g./in.

The solution also contained suspended 0.75 phr. of accelerator, namely,2-rnercaptoimidazoline and 4 phr. of magnesium oxide. After evaporationof the solvent the treated canvas uppers were fixed on a shoe moldingmachine form and a compound designed for both soling and foxing injectedinto the mold. The injection molding conditions consisted of a polymermelt temperature of about 400 F., injection pressure of 250 p.s.i.(gauge), pressure within the mold of p.s.i. (gauge). Injection time wasabout 3 seconds and the formed shoe assembly was held in the mold forapproximately one additional minute to allow the thermoplastic rubbercompound to become firm through cooling. The compound used for thislatter purpose comprised parts by weight of a block copolymer, parts byweight of a naphthenic mineral rubber extending oil, 30 parts by weightof crystal polystyrene, 85 parts by weight of an inorganic filler,namely, clay and titanium dioxide mixture, and 1 part by weight ofantioxidant. The formulation also contained 25 parts by weight of thezinc oxide which acted as a curing agent for the polychloroprene.

In order to test the effectiveness of the polychloroprene treatment, aparallel test shoe assembly was prepared utilizing all of the sameconditions and components with the exception of the polychloroprenetreatment and the zinc oxide component of the soling and foxingcompound. The resulting shoes were tested in the Instron tester underboth wet and dry conditions. The shoe assembly having thepolychloroprene treatment had wet and dry peel strengths of 14 poundsper linear inch. Contrasted to this, the shoe assembly in which thepolychloroprene treatment was omitted had a dry peel strength of 15p.l.i. while its wet peel strength was only 9.0 p.l.i.

The block copolymer used in both shoe assemblies had the structurepolystyrene-polybutadiene-polystyrene, the block molecular weights being23,00041,00023,000.

EXAMPLE HI Tests were performed to determine the effect of varying thetype of solvent by which the polychloroprene was applied to the canvasuppers insofar as wet peel strength of the block copolymer foxing wasconcerned. At the same time further comparative tests were made todetermine the effect of polychloroprene treatment of the convas versusno treatment since there was a change in the foxing formulation fromthat described in Example I. For the present tests, the same canvaslaminate was utilized cut into the shape of tennis shoe uppers.Comparative samples were treated with polychloroprene, one by means of achloroform solution and the other by means of a methyl ethylketone/hexane solution. The block copolymer compound described morefully hereinafter was utilized for injection molding of a soling andfoxing onto these treated uppers. The wet peel strength of the foxingwas found to be 27 pounds per linear inch for the shoe assembly treatedwith polychloroprene in chloroform solution and compared with pounds perlinear inch for the shoe assembly in which the canvas was treated withpolychloroprene in methyl ethyl ketone/hexane solution. The comparableshoe assembly was prepared in which the foxing and soling was moldedonto the convas uppers in the absence of any prior treatment withpolychloroprene. The wet peel strength in this instance was only 6p.l.i.

The block copolymer formulation utilized for soling and foxing was asfollows:

Parts by wt. Block copolymer 100 Naphthenic mineral rubber extending oil110 Crystal grade polystyrene 60 Mineral filler 90 Zinc oxide, when usedAntioxidant 1 EXAMPLE IV Tests were performed to determine the wet anddry peel strengths of shoe assemblies with and without a polychloroprenetreatment as in Example 11 except that the polychloroprene solutioncontained 5 phr. of suspended zinc oxide in addition to 0.75 phr.Z-mercaptoimidazoline and 4 phr. of magnesium oxide, and the foxingcompound used contained no zinc oxide. In this case a wet peel strengthof p.l.i. was obtained for the shoe assembly having the polychloroprenetreatment, compared to 7 p.l.i. for the untreated shoes. Dry peelstrengths were 13 p.l.i. for the treated foxing and 11 p.l.i. for theuntreated foxing.

EXAMPLE V Tests were performed to determine the wet and dry peelstrengths of shoe assemblies with and Without polychloroprene treatmentafter laundering and drying the fabricated shoes in a householdautomatic washer and dryer through two separate cycles. Thepolychloroprene treatment and foxing compounds were essentially the sameas those in Example 11. The wet and dry peel strengths ofpolychloroprene-treated shoe assemblies were 16 and 15 p.l.i.,respectively, while those of nontreated shoes were 6 and 5 p.l.i.,respectively, after two complete cycles of washing and drying.

EXAMPLE VII Comparative tests were performed on shoe assemblies with andwithout a resin treatment. Canvas sheeting was laminated with a curedSBR combining paste to form a canvas laminate which was cut into theform of tennis shoe uppers. The area which was to be contacted with thefoxing strip was treated with a melaine-formaldehyde prepolymer inaqueous solution (1040% w.).

The solution also contained 3.5% by weight of ammonium chloride and 26%of magnesium chloride based on the weight of preploymer. Afterevaporation of the water the treated canvas uppers were heated for 3minutes at 350-375 F. to cure the resin and then were fixed on a shoemolding machine form and a compound designed for both soling and foxinginjected into the mold. The injection molding conditions consisted of apolymer melt temperature of about 400 F., injection pressure of 250p.s.i. (gauge), pressure within the mold of p.s.i. (gauge). Injectiontime was about 3 seconds and the formed shoe assembly was held in themold for approximately one additional minute to allow the thermoplasticrubber compound to become firm through cooling. The compound used forthis latter purpose comprised parts by weight of a block copolymer, 108parts by weight of a naphthenic mineral rubber extending oil, 60 partsby weight of crystal polystyrene, 90 parts by weight of an inorganicfiller, namely, clay and titanium dioxide mixture, and 1 part by weightof antioxidant.

In order to test the effectiveness of the melamineformaldehydetreatment, a parallel test shoe assembly was prepared utilizing all ofthe same conditions and components with the exception of themelamine-formaldehyde treatment. From the resulting shoes one-half inchstrips cut from the foxing area were tested in the Instron tester at 0.2inch per minute grip separation rate under both wet and dry conditions.The shoe assembly having the treatment had a dry peel strength of ll-14pounds per linear inch and a wet peel strength 10-12 p.l.i. Contrastedto this, the shoe assembly in which the melamine-formaldehyde treatmentwas omitted had a dry peel strength of 11 p.l.i. while its wet peelstrength was only 7 p.l.i.

The block copolymer used in both shoe assemblies had the structurepolystyrene-polybutadiene-polystyrene, the block molecular weights being23,00041,00023,000.

EXAMPLE VIII The extent of foxing separation of shoes treated accordingto the present invention were compared with shoes which did not have thetie-coat treatment, referred to below as control samples. Testing was bymeans of actual wear tests for the periods indicated in the followingtable:

Foxing separation area ratio variable} control Maximum depth of foxingseparation tie coat (el Weeks on test variable control The uppersutilized in the shoes tested were canvas duck. The soling and foxingcomposition in samples A-D was that described in Example I. The solingand foxing composition in samples E and F was altered in that thepolystyrene content was reduced to 30 parts by weight, other componentsbeing present in the proportions specified in Example 1. PVC refers topolyvinyl chloride.

We claim as our invention:

1. In a footwear assembly comprising a textile upper, a polymeric solingand a foxing, the improvement comprising a polymer tie coating on atleast the area of the upper which is covered by the foxing, said foxingcom prising a block copolymer having the general configuration selectedfrom the group consisting of wherein each A is a polymer block of amonovinyl arene, B is a polymer block of a conjugated diene, and n is awhole interger between 1 and 5, the tie-coating polymer having a tensilestrength of at least pounds per square inch and a dielectric constant atleast equal to that of the block copolymer, the wet peel strength at 23C. of the textile-tie coat-foxing assembly being at least about 70% ofthe dry peel strength of said assembly at 23 C.

2. An assembly according to claim 1 wherein the tiecoat polymer is atleast one polymer of the group consisting of polymers of vinyl halides,amine-aldehyde copolymers, phenolics, phenol-aldehyde copolymers,halohydrocarbon polymers, epoxy resins, cellulose ethers, and esters,ABS polymers, polyurethanes, acrylate polymers, methacrylate polymers,the area of foxing separation during 1 1 1 2 Wear tests of shoes isreduced by a factor of at least two References Cited compared withcontrol shoes bearing no foxin tie coat. UNITED STATES PATENTS 3. Anassembly according to claim 1 Wherein the block 145 487 8/1 6 copolymerhas the structure polystyrcne-polybutadiene- 25 3 3 5532:;

2g t ir zsembly according to claim 3 wherein the textile 5 329349412/1966 Fischer 3,373,150 3/1968 Pears et al 26092.8

is a cellulose-based textile.

5. An assembly according to claim 4 wherein the tiecoat polymer is apolymer of vinylidene chloride. PATRICK LAWSON Pnmary Exammer

